1. Technical Field of the Invention
The present invention relates to novel s-triazine compounds containing three particular para-aminobenzalmalonate substituents and to the cosmetic applications thereof.
This invention also relates to photoprotective cosmetic compositions comprising s-triazine compounds containing three grafted para-aminobenzalmalonate substituents as sunscreens that are active in the UV radiation range.
2. Description of Background and/or Related and/or Prior Art
It is known that radiation with wavelengths of between 280 nm and 400 nm permits tanning of the human epidermis, and that radiation with wavelengths of between 280 nm and 320 nm, known as UV-B radiation, causes skin burns and erythema which may be harmful to the development of a natural tan.
It is also known that UV-A rays, with wavelengths of between 320 nm and 400 nm, which cause tanning of the skin, are liable to induce an adverse change in the latter, especially in the case of sensitive skin and/or of skin which is continually exposed to solar radiation. UV-A rays cause, in particular, a loss of elasticity of the skin and the appearance of wrinkles, leading to premature skin aging. They promote triggering of the erythemal reaction or amplify this reaction in certain individuals and may even be the cause of phototoxic or photoallergic reactions. Thus, for aesthetic and cosmetic reasons, such as the conservation of the natural elasticity of the skin, more and more individuals wish to control the effect of UV-A rays on their skin. The term “sun protection factor” means the ratio of the irradiation time required to reach the erythema-forming threshold in the presence of the test screening agent to the irradiation time required to reach this same threshold in the absence of screening agent.
It is thus desirable to provide compounds capable of absorbing UV-A rays.
Besides their power for screening out UV-A radiation, the desired photoprotective compounds must also have good cosmetic properties, good solubility in the usual solvents and especially in fatty substances such as oils and fats, and also good resistance to water and to perspiration (remanence) and satisfactory photostability.
Among all the compounds that have been recommended for this purpose, mention may be made especially of the s-triazine derivatives bearing benzalmalonate substituents described in EP-0,507,691 by the assignee hereof. However, these compounds have a liposolubility and a photochemical stability that are still not entirely satisfactory.